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POWhy C# threads goes idle during the execution?
 

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  1. POWhy C# threads goes idle during the execution?
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    <p>I have a scheduler which runs as background thread on application start of an ASP.NET site. User can initiate various tasks (alert emails/file generation etc) which is inserted in a db table. The scheduler will pick the tasks from database and push the items into a stack. Also scheduler has a threadpool running 10 background threads, which will pop task items from the stack and execute it.</p> <p>This is running fine in one web server, but behaving strange in other web server. The threads goes idle for 6-12 seconds with no reason and do nothing even though there are items in the stack. </p> <ul> <li>Using lock() on stack object to make Push &amp; Pop thread safe</li> <li>Tried Thread.Yield() to give yield to cpu to execute other threads, but slowing down the execution and going idle still persists</li> <li>Tried Thread.Sleep(0) to give yield to cpu to execute other threads, but slowing down the execution and going idle still persists</li> <li>Logged entries and exit of all methods to check if something going wrong during the execution, but no luck</li> </ul> <p>My questions:</p> <ol> <li>Is execution of threads in .net in-deterministic?</li> <li>Is it necessary to specify Thread.Yield() or Thread.Sleep(0) to give breathing time to cpu?</li> <li>Why it is behaving differently on boxes with same configuration? Is there any machine/environment specific factors that affect the execution of thread?</li> </ol> <blockquote> <p>UPDATE on May.08.2013</p> </blockquote> <p>There are two boxes in the farm, both are identical in hardware configuration, setup with same software configuration as well Windows 2008 64bit / IIS7. Both webserver has only one site each with same build. Application pools of both site runs on Framework V4.0 on integrated mode. This is a legacy code and no chance since last two years.</p> <p>We tried several iterations, in all cases webserver1 executes without any issues and completes the background work quickly as it was earlier. <strong>BUT webserver2 has significant delay and performing very poor.</strong></p> <p>We tried extensive logging, capturing entries/exit of all methods. The scenario is like this, all threads works fine for 2 seconds and then goes idle for 6-12 seconds, again become live and execute for next 2 seconds and then goes idle again. This behavioral is consistent till the completion of the task. There is no exception, no application termination, no error in application pool/iis log.</p> <p>Any idea ?</p>
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    1. CO1. Yes. 2. No. 3. You probably have a bug/race condition that only one configuration is capable of bringing out; without knowing more about the code this is hard to know for sure though.
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    2. CO@Servy Why the execution of thread slowing down when using Thread.Yield() or Thread.Sleep(0)?
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    3. CO@Servy the orginal code is complex, however i have updated the question with mock code.
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